Be mad keen on one - Idioms by The Free Dictionary
be mad keen (on someone or something) (redirected from be mad keen on one)
be mad keen (on someone or something)
To be very enthusiastic or excited about someone or something. Oh, I've seen the way Tim smiles at you—he's definitely mad keen on you! I'm mad keen on that college, so I really hope they accept me.
be mad ˈkeen (on somebody/something) (informal) be very interested in or enthusiastic about somebody/something: She’s been mad keen on African music ever since she came back from Zimbabwe last year. ♢ He’s mad keen on getting into the army.